Semiconductor devices having a resistor terminal (such as a dynamic memory device) require to detect whether the resistor terminal is coupled to an external resistor. Generally, a detection mechanism of semiconductor devices is capable of distinguishing whether the external resistor exists, but it is not considered the circumstances if connecting to the external resistor or not. Currently, under the circumstances without connecting to the external resistor, there is no available mechanism to detect whether the resistor terminal is coupled to an operation voltage, a ground voltage, or a floating.